Ammonia and phosphorus removal from mixture of treated and raw cattle manure wastewater in a low‐O2 granular sequencing batch reactor

Abstract

AbstractBACKGROUNDIn this study, the feasibility of an aerobic granular sequencing batch reactor (AGSBR) for elimination of nutrients at low dissolved oxygen (DO) level was investigated. It was fed by a mixture of treated and raw cattle manure wastewater. The behaviour of the AGSBR was assessed at different chemical oxygen demand (COD)/NH4+‐N ratios, feeding strategies (dump‐fill and slow‐rate feeding) and hydraulic retention times (24, 32 and 48 h). For a duration of 140 days, the capability of the AGSBR for reducing COD, ammonia and total phosphorus (TP) contents was studied. At DO concentrations of 0.3–1.0 mg L−1, the effect of different COD/NH4+ ratios (100:3–100:10) was evaluated.RESULTSA COD/NH4+‐N ratio of 100:10 resulted in higher nitrification rate (0.0714 gN gMLVSS−1 day−1) compared to a ratio of >100:3 (0.0175 gN gMLVSS−1 day−1). The active granular sludge in dump‐filling mode revealed better settling properties compared to the slow feeding rate. Microscopic observation of aerobic granules showed that the core of granules was dominantly occupied by filamentous microorganisms. Finally, at optimum conditions, removal efficiencies of NH4+‐N, TP and COD were 99.9, 99 and 79%, respectively.CONCLUSIONSApplying the AGSBR at low DO is promising as a cost‐effective technique for the secondary treatment of livestock wastewaters. © 2019 Society of Chemical Industry